Cellulose ester.



iinrrn srA rns PATENT OFFICE.

I-IARRY S. MORK, OE BOSTON, MASSACHUSETTS,ASSIGNOR TO CHEMICAL PRODUCTS COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF MAINE.

CELLU LOSE ESTER.

Specification of LettersPatent.

Patented May 21, 1907.

To a, whom it may concern,-

Be it known that I, HARRY S. Mean, of Boston, county of Suffolk, State of Massachusetts, have invented an Improvement in Cellulose Esters, of which the following description is a specification.

My invention relates to the manufacture of organic esters of cellulose, and particularly to the production of cellulose esters of the fatty acids in which through the exercise of my invention there is substantially retained the fibrous, or other form of the original cellulose structures from which they were derived.

Organic esters of cellulose, such as cellulose acetate, have heretofore only been producedby methods which have involved as a necessary consequent of their successful application the complete b eakdown and destruction of the physical form of the cellulose structure concerned in the reaction, and the recovery of the degraded acetate, either in solution or ultimately horny masses; or else, where attempts to conserve the structure have been made the product has been so harsh and brittle as to break down into mere fragments, even under the slight mechanical strains of washing and handling. It is obvious that such products have neither'practical nor commercial value in the wide range of applications requiring the manipulation of a firmer product and the retention of the fiber as a part of the final structure. Where others may have produced acetylated fiber fragments my process permits the production, for the first time, of acetylated cellulose in which the'physical form and characteristics of the original fiberused is substantially conserved.

My process may best be carried out at the ordinary temperature, or say from 152O (1., whereby all danger of the Well-known olegrw dation of the ester, which takes place at substan ti ally higher temperatures, is eliminated. I accomplish this latter resultin the operation of my process by first converting the cellulose into a characteristic form of hydrocellulose, as hereinafter fully described.

By my process the original form of the cell ulosic raw material entering the esterizing b ath n ay be substantially conserved throughout the subsequent stages of the process and in the resulting ester, for which reason, together with the fact that by my process the ester maybe and preferably is produced at the normal temperature, the production of organic esters of cellulose of a quality and struc ture hitherto unknown and with wholly new properties and possibilities for constructive purposes is rendered easy. It is with these new sorts of organic esters of cellulose that my invention is particularly concerned, although it is also directed to and involves the method of their preparation.

I have discovered. that esterification may be effected at the ordinary temperature in a 6 5 I produce such a bath 7 agents primarily concerned in the esterifica- 7 5 tion and a non-solvent of the desired ester. The benzol or its equivalent thus incorporated in the bath not only serves to dilute the esterizing agents and thereby restrain and moderate the velocity of the reaction,

thus insuring more complete control thereof and avoiding the otherwise drastic action of the reagents upon the aggregated cellulose molecules, but also prevents the ester from passing into solution in the bath, my entire 8 5 process conserving, in the product, the structure of the original cellulosic raw material and avoiding the degradation of the ester which always and necessarily occurs when it is dissolved even at the ordinary temper- 9o ature in the powerful reagents involved in its production,

In carrying my invention into effect, as in the manufacture of cellulose acetate, I prematcrial, which may be purified cotton in the form of flock, roving, yarn or fabric, is first converted into a more reactive but still fibrous modification of cellulose, which. I regard as a fibrous form of hydrocellulose. 10b

The term hydrocellulose is generally understood to apply to a product formed by the for to proceed as follows;-The celluloseraw 1 i "'Lll'y tins ester as the normal cellulose triacetate (C ILO (CH CO) This equation shows the general formation of the normal triacetate of cellulose from cel-- lulose, but, does not indicate how the initial formation of hydrocellulose' renders possible. the production of this normal triacetate of cellulose, nor does the present universal lack of knowledge of the constitutional structure of the cellulose molecule warrant an attempt to graphically represent this essential feature of my process.

WVhat I claim as new and desire to secure by Letters Patent is 1. The process of preparing cellulose acetate which consists of converting cellulose into a hydrocellulose of the character described and thereafter effecting the acetylation in the presence of a restraining agent in which the cellulose acetate is insoluble thereby conserving the fibrous structure of the original cellulose.

2. The process of preparing cellulose esters which. consists of converting cellulose into a hydrocellulose of the character described and thereafter effecting the esterification in thepresence of a restraining 'agent in which the cellulose ester is insoluble thereby conserving the fibrous structure of the original cellulose.

3. The process of preparing cellulose acetate which consists of converting cellulose in substantially the form of the cellulose structure from which it was derived and pos .sessing in a relatively high degree the properties of a colloid.

5. As a new article of manufacture, normal, fibrous non-friable cellulose triacetate in the form of the vegetable fiber from which it was derived and possessing in a relatively high degree the properties of a colloid.

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing witnesses.

HARRY S. MORK. 

